Honnestly backstab and highground are the most usual OP mechanics in the game... and you have to exploit them to succeed. This is the minimum requirement and if a strategy game with tons of spells, features and so-called "choices" turns arround 2 mechanics, I call this a bad balance.
Well, for me the easiest of the previously challenging fights was with a druid party (level 3) against the redcaps. Found a narrow path, then shifted the druid in spider form and cast web, started combat via ranged attack and then kept plinking away. It took some time, as the ranged hit chance was mediocre, but the spider can keep spamming web indefinitely. I had to use one of those void bulbs to keep them in the webs, but that is because I didn't have any characters with thunderwave or repelling blast. So I don't think you need backstab etc. when it comes to level-appropriate content. However, currently the characters are locked at level 4, while I suspect the githyanki & underdark are level 5 content.
Now druid no. 2 is on the way, but this time Wyll wisely chose repelling blast.
